UC3842 SMPS 500W

[Nenad Grujic]

"Тут картина как раз наоборот, В сварочниках чаще ставят обычные диоды в паралель поскольку на токи сварочника проще поставить пачку обычных чем искать шотки на такие токи."
Hepo , can you please explain me this , I'm not sure that I m understand what you won say ?

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[Nenad Grujic]

Today I m replace damage FET and put new , and all so connect LOAD direct to secondary side on smps , after few min work FET is total cold and LOAD is very hot , that look me like good way .
I m see that signal on FET is not total quadratic , maybe because now power come from 310V from capacitor and 10 k resistor for start and after when smps start work come from transformers secondary coil who is wind only for power PWM part , and I have  in serial connection 45R resistor  on power network  ?
First image is  signal wave from PWM part  to Q2 FET and second is  voltage wave on secondary side with 15R resistor like LOAD .

Have you idea why have that wave deformation and if you better look you can see some oscillation on dead time , that is wrong snuber or ?

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[Nenad Grujic]

Today I m try run voltage regulation on secondary side and again allot problems .
For voltage regulation I m use TL431 , and plane is have regulation from 15V to 24V .
I m calculate voltage with formula Uout=(1+R1/R2)*Vref , and if you look my circuit diagram then R10 is 43 k , R14 is 8,2k and R15 is 25k (all so try with 50k but same ) and have only 4V difference with max. and min. position for R15 , can say that not work how I m plane , and that is from 15V to 24V .
All so second problems is nex. , plane is that for start SMPS first voltage for run will be come from capacitors (310V ) through R6 , on this test 10 k resistor 3W , and after start SMPS use supplay from transformers on switcher and have rectifier with fast diode , when supply come from resistor 10 k then voltage is 10V , enough for first run and when supply come from transformers then have 18V and then current not need come from 10 k resistor or if will be then will be small , but on real work that not work correct , have you idea how do that ?

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 Обязательным условием долгой и стабильной работы Li-FePO4-аккумуляторов, в том числе и производства EVE Energy, является применение специализированных BMS-микросхем. Литий-железофосфатные АКБ отличаются такими характеристиками, как высокая многократность циклов заряда-разряда, безопасность, возможность быстрой зарядки, устойчивость к буферному режиму работы и приемлемая стоимость. Но для этих АКБ, также как и для других, очень важен контроль процесса заряда и разряда, а специализированных микросхем для этого вида аккумуляторов не так много. Инженеры КОМПЭЛ подготовили список имеющихся микросхем и возможных решений от разных производителей. Подробнее>>

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[Nenad Grujic]

Hi folks
 

I'm redesign circuit diagram for my smps , now look me that  signal is ok , have only one problems with secondary side control voltage  , need invert principle , on this moment when optocoupler is not active then signal have bigger delay , and when is active then  delay is low , but on real need  invert that , need have low delay when optocoupler is active .
Have you idea how I can do that on PWM IC side , not on secondary side , or maybe can on secondary side but need be stable in work ?

First image (DSC_0123.jpg) is with not active optocoupler on secondary voltage regulation  , second image (DSC_0124.jpg) is with active optocoupler  but like you can see need invert that .

SG3525-500W-SMPS-V4.1-schematic.pdf

[Nenad Grujic]

Hi all
Can some one give me answer on  few next question :
I have EE4215 core  who work on 62 kHz frequency and  material for core is ZP40 (need  be similar like N84 or PC40 ) , max power on 62 kHz is something like 690W and I'm test is on 500W , but  my core or transformers is so hot on long work time , with fan that is 85 degree , without is 117 degree , have you idea why have that allot heating on transformer ?
Secondary side coil is  make it with Cu foil 23 mm width and 2x5 turns  , that foil is ok for constant 21A and work on 62 kHz  ?
Primary side is 24 turn , 4 x 0.5 mm wire , that is ok  if we are measure that input current is 2.26A ?

Thanks for help